Leading-in conductor.



No. 789,515. PATENTED MAY 9, 1905. W. R. WHITNEY. LEADING-IN CONDUCTOR.

APPLIOATION FILED SEPT. 14, 1904.

Figs. 1.

Inventor: Willis R. W

Witnesses STATES Patented May 9, 1905.

PATENT FFICE.

"WILLIS R. WHITNEY, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NETV YORK.

LEADING-4N CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 789,515, dated May 9, 1905. Application filed gepteinher 14, 1904. Serial No. 224,392.

Be it known that l, W ILLIS R. WHITNEY, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Leading-in Conductors, of which the following is a specification.

In the manufacture of incandescent lamps, mercury-vapor lamps, mercury-reetifiers, and apparatus of a similar nature in which a glass or vitreous envelop is used it is necessary to provide leading-in wires for conducting electrical energy from the power-circuit to the space inclosed by the sealed bulb. Platinum is well suited for use in apparatus of this type, as its coellicient of expansion is substantially equal to that of glass, and hence changes in temperature do not destroy the seal. The great cost of platinum is, however, a serious objection to its extensive use for such purposes, and many efforts have been made to secure a suitable substitute. It has been found that certain alloys of iron and nickel have a temperature eoeflicient very nearly if not exactly that of the glass used for such vessels; but nevertheless great difiiculty has been experienced in making seals which will be absolutely air-tight and permanent in character. I believe that one cause for the unsatisfactory results sometimes obtained in the commercial use of such alloys arises from the fact that the alloys have the power of absorbing large quantities of gas or gases which are retained by the alloy until it is heated to effect the sealing operation; but when so heated the gas is given out in large quantities and forms bubbles in the glass around the conductor, and thus materially decreases the mechanical strength of the seal and increases the liability of leakage. WVhile I do not attempt to state positively what the chemical composition of this gas is or how it is retained by the alloy, nevertheless I believe it probable that the gas consists principally of hydrogen and that it is retained in an uncombined state in the min ute pores of the alloy. I have, however,

made this important discovery that if the gas or gases are once tl'ioroughly removed by a suitable process and the alloy is properly cooled before being again brought in contact with air or other gas the alloy will remain substantially free from gas for a day at least.

By my process I am able to treat metals and alloys in the shape of wires, bars, and other commercial forms, and after extracting the gas or gases I may freely expose them to the air and subsequently use them in the manufacture of lamps and other articles in the same manner as platinum has heretofore been used.

In the drawings, Figure 1 shows one form of apparatus in which alloys treated by my process may be used. Fig. 2 shows the effect of scaling in a nickel-iron wire without removing the occluded gases, and Fig. 3 shows the tight seal effected with a wire which had been treated to remove the gases.

The mercury-vapor lamp 1 is of the wellknown type in which the current enters through the terminals 2 3, sealed in the extremities of the tube. The starting-filament t, anchored by the brackets 5 6, makes electrical contact with the iron plunger 7, Heating in the mercury 8, by means of a small quantity of mercury carried in the cupped top of the plunger. This plunger is drawn down when the lamp is started by the magnetic action of the solenoid 9, thus forming a spark between the filament 4 and the mercury carried by the iron plunger 7, and so starting the mercury-vapor are between the mercury 8 and the upper electrode 10.

In Fig. 2 is illustrated an enlarged View of the terminal 3, showing the efleet produced when wires of iron-nickel alloy of commercial composition and condition are sealed into the glass, a great number of bubbles having formed in the glass about the terminal when the sealing operation was being performed.

Fig. 3 shows a seal formed from wire treated by the process herein described.

The alloy to be treated, preferably in the form in which it is to be used, is heated to a high temperature in a vacuum-furnace, which may be of any of the well-known commercial forms, in which means is provided for con tinuously exhausting the vacuum-chamber while the heating operation is being carried.

on; The alloy is maintained at a temperature of about 1,100 centigrade for approximately a half-hour, during which time it gives off practically all of the occluded gases. These gases are pumped out of the chamber as fast as liberated by the alloy. Practically all traces of oXids disappear from the surface of' the alloy and the surface becomes clean and bright. At the expiration of the halfhour the heat is turned OE and the metal allowed to cool in the vacuum-chamber until practically cold. This probably allows the pores of the metal to close and possibly produces other changes in the structure of the alloy; but whatever the effect may be I have found that the alloy when removed from the furnace has a clear silver-like lustre and that it may then be successfully sealed into glass vessels, giving a clean tight seal free from bubbles and very strong and durable.

Vhatl claim as new, and desire to secure by Letters Patent of the United States, is

1. The process of removing occluded gas from a conductor which consists in heating a conductor in a rarefied atmosphere at a temperature below the melting-point of said conductor and subsequently cooling said conductor in a rarefied atmosphere.

2. The process which consists in heating a conductor in a rarefied atmosphere at a temperature below the melting-point of said conductor, cooling said conductor in a rarefied atmosphere, and subsequently embedding the conductor in vitreous material.

3. The process of removing occluded gas from alloys which consists in heating the alloy in a rarefied atmosphere, cooling said alloy and maintaining a rarefied atmosphere about said alloy while the alloy is cooling.

4. The process of' removing gas from alloys which consists in heating the alloy in a rarefied atmosphere at a temperature below the melting-point of said alloy and maintaining a rarefied atmosphere about said alloy until the alloy has cooled.

5. The process of treating alloys containing iron and nickel which consists in heating said alloy in a rarefied atmosphere at a temperature below the melting-point of said alloy, cooling said alloy in a rarefied atmosphere and subsequently coating said alloy with vitreous material.

6. The process of treating an alloy which consists in heating said alloy at approximately 1,100 centigrade for a prolonged period in a rarefied atmosphere, cooling said alloy, maintaining a rarefied atmosphere about said alloy while the alloy is cooling and subsequently coating the alloy with vitreous material.

In witness whereof I have hereunto set my hand this 10th day of September, 1904.

\VILLIS R. XV'HITNEY.

Witnesses:

BENJAMIN B. HULL, HELEN ORFoRD. 

